52 Conservation Department 



extend far below the upper 10 m. for in general the temperature 

 dropped off sharply below this point, the exceptions occurring in 

 tlie eastern end of the lake and along the American shore — both 

 regions of ''pile up" due to the prevailing southwest winds. 



The water in the trench off Long Point was apparently true 

 winter water still practically at minimum temperature and maxi- 

 mum density and the occasional storms which had blown across the 

 surface above it since the water began to warm up in the spring 

 had not been strong enough to overcome the steadily increasing 

 stability of equilibrium into which the warm weather was putting 

 the water. 



The second cruise of the Shearwdfer was given over to fishing 

 with the trawls, but on the third cruise, August 15, 16 and 17 the 

 mean surface temperature had risen to 22.9° and the mean temper- 

 ature of the 10 m. level to 21.3° showing the water to be thoroughly 

 mixed in the upper ten meters. 



But the most remarkable feature of the lake at this time was 

 the very low tem])erature found at the bottom at stations 3 to 10, 

 caused by a great spreading out to the eastward of the water which 

 had ]^reviously been confined to the trench off' Long Point. Ham- 

 pered as we are when dealing with fresh water by the absence of 

 salinity values as identifiers, the complete absence on the first cruise 

 of any water below 20° to the eastward of the line of stations 

 3-4-5 is proof positive that the Avater below 15° now found at 

 these stations could have come there only from the .west, that is 

 from the deep hole. 



Something had set this cold mass in movement and against the 

 action of gravity it Avas rising over the slopes which surround its 

 place of origin and creeping under the lighter surface water until 

 it encountered some obstacle to its progress. In the region of 

 Dunkirk where it had been halted by the shore its presence was 

 manifested in the low surface temperature as well as the bottom 

 for in these shallows the water was thoroughly mixed from top to 

 bottom. It had not a])parently extended far enough to the east- 

 ward to make itself felt at stations 1 and 2 nor had it gone around 

 the corner into Long Point bay as far as station 18, but it had 

 affected the bottom temperatures of practically all the other 

 stations. 



The question at once ]nTsented itself whether this cret ping of 

 cold water to the eastward was a normal flow of the eutii'e lake 

 water toward Buffalo — a flow Avhich would pi-eseiilly drain the 

 deep hole of cold water and re])lace it with wannef water from tlie 

 western end of tli<' lake — or whether it was an oscilhitoi'v moN-ement 

 of the natnre of a submarine sei('h(\ 



A theoi'v can l)e advanced wliich accords fairly well with the 

 c()m|)nte(l "noi-iiial hik(^ moveiiicnl " (to be discussed later") which 

 wouhl cxphiin why cohl water had not appeared off I'oinl Abino 

 earlier in Ihe season and \'el did appear now ; I»n1 i1 was reeogni/.ed 

 that a sei(die nioN'enietd was far more likely to furnish th.e explan- 

 ation, and 1enipei-a1 ures taken from sintion 1 1o stnlion !) on the 



